Added 6 college hackathons accepting hs students w/registration still open.
Added 6 college hackathons accepting hs students w/registration still open.

Added Winter WonderHack, HackTCNJ, Hack UMBC, ProfHacks, GrizzHacks and CatHacks II.
Note: SpartaHack accepts hs students but registration is closed so not added.
Note: img's not included in PR.
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